1. Field of the Invention
The present invention relates to processing video signals in different video formats, and particularly relates to an apparatus that can facilitate working with such differently formatted video signals.
2. Description of the Related Art
Processing and displaying video signals has many applications in fields as varied as closed-circuit television and medical imaging, as well as in commercial broadcast, cable and satellite television. A video signal typically consists of a serial stream of data that represents moving image data. More specifically, such data typically represent consecutive still images (frames) that when viewed in sequence convey a sense of motion. In fact, if such frames are captured and then displayed to the viewer quickly enough (i.e., at an adequate frame rate), the display of such discrete frames is perceived by humans as true continuous motion video. For this to occur, the frame rate typically must be at least approximately 20 frames per second, although frame rates as low as 8 to 12 per second may be used in some cases if a sufficiently high flash rate is used. At slower flash rates, flicker may be visible and/or the motion may appear to the viewer to be discontinuous.
The serial data (in analog or video format) comprising a video signal typically is originally generated by repetitively scanning a moving image, which has been focused by a lens system, in a sequence of horizontal scanning lines from the top to the bottom of such image. In one variation (called xe2x80x9cnon-interlacedxe2x80x9d or xe2x80x9csequentialxe2x80x9d), all horizontal lines are scanned in each pass from top to bottom. In another variation (called xe2x80x9cinterlacedxe2x80x9d), for each frame only the odd lines are scanned in a first pass and then only the even lines are scanned in a second pass. In such interlaced formats, the collection of all odd lines for the frame is termed a xe2x80x9cfieldxe2x80x9d and the collection of all even lines for the frame is another field, meaning that each frame consists of two separate fields.
Thus, as used herein, the term xe2x80x9cvideo signalxe2x80x9d is intended to mean a stream of data or an analog signal representing a succession of image frames. As indicated above, a video signal may represent a moving image. Such a moving image video signal is referred to herein as a xe2x80x9clive video signalxe2x80x9d, regardless of whether such video signal is being currently generated or retrieved from a storage medium. It is also possible for the succession of frames represented by a video signal to consist of identical frames. Typically, in such a case the same frame is being scanned repetitively. The situation in which the video signal represents such a succession of identical video frames is referred to herein as a still frame or single frame video signal. In the case of a still frame interlaced video signal, the two fields may or may not be identical.
For some time now, a number of different video signal formats have existed. For example, the standard video format in the United States (the National Television Systems Committee, or NTSC, standard) includes 525 horizontal lines per frame. Only 483 of these lines are xe2x80x9cactivexe2x80x9d, i.e., include actual image information, with the remainder including synchronization and other information. In contrast, the standard format in Europe includes 625 horizontal lines per frame, of which only 576 lines are active. Both of these standards are examples of interlaced standard definition (SD) video formats.
In recent years, the number of video formats in use has increased substantially, particularly as the result of work in the area of digital television that includes high definition (HD) format television. For example, there are currently 18 different SD arid HD formats that have been authorized by the Federal Communications Commission (FCC) for use in the digital television broadcast frequencies. Many of the HD formats are non-interlaced formats, although currently the dominant HD format is interlaced. The most common HD formats have spatial resolutions of 1920 by 1080 pixels and 1280 by 720 pixels, respectively, as compared with the NTSC format which has a spatial resolution of 720 by 483 pixels.
Over time, it is expected that many commercial broadcast markets will transition to HD standards. However, in the meantime, for a number of reasons, not the least of which is the substantial investment in equipment and consumer devices that are only capable of handling SD formats, various HD video formats are likely to co-exist with the now commonly used SD video formats for many years to come.
Moreover, beyond the context of commercial broadcasting, a number of additional video formats have been employed in various contexts. For instance, in the field of medical imaging, it is common for different specialized video formats to be used for magnetic resonance imaging (MRI) and for computer-aided tomography (CAT) imaging.
In addition to characteristics such as spatial resolution and whether the signal is interlaced or non-interlaced, the various video formats may be differentiated by any or all of: pixel aspect ratio, image aspect ratio, the color space in which the image is defined, whether subsampling has been used, and (for digital images) the number of quantization levels in which each element of a picture""s color is represented. Thus, conversion from any particular format to any other particular format often is not a simple matter and typically has been accomplished using special-purpose hardware.
Nevertheless, in many situations it is desirable to work with and/or to combine video signals having different formats. For example, as HD becomes more commonplace, it is increasingly important to be able to quickly combine, or to be able to quickly transition between, a particular SD format video source and a particular HD format video source for television broadcast/transmission purposes. Similarly, for example, it may be desirable to quickly incorporate a relatively short MRI video segment into a standard NTSC transmission.
Unfortunately, the present inventors have discovered that it is often quite difficult to accomplish such tasks with conventional techniques. In particular, such conventional techniques typically require the user to disconnect an existing hardware configuration, locate the appropriate special-purpose hardware conversion unit, and then reconfigure the system, whenever a new video format is introduced or required as an output.
The present invention addresses the foregoing problem by providing apparatuses and related techniques for managing video signals in different video formats. For example, the present invention can be implemented using multiple channels in which input and output devices having different formats can be connected on different channels, with each channel having access (in its own format) to the video image data input on any other channel or to any video image data retrieved from storage, with all format conversion occurring automatically, and with the format for each channel being user-selected: As an alternative example, the present invention can be implemented using a single channel, having access (in its own format) to any video image data retrieved from storage, with all format conversion occurring automatically, and with the format for the channel being user-selected. Various other combinations of such features (as well as the other features described herein) can be provided in other implementations of the present invention.
Thus, in one aspect, the invention is directed to managing video signals in different video formats by inputting and outputting video signals through multiple channels, with each such channel having an associated video format. A user designation is input that an output of a user-designated first channel should provide an output video signal corresponding to an input video signal input via a user-designated second channel. The input video signal is then automatically converted to the video format associated with the user-designated first channel, so as to obtain the output video signal, and the output video signal is output via the user-designated first channel.
By virtue of the foregoing arrangement, the output of a channel operating in one video format can be made to track a video signal that is input into another channel operating in a different format. Moreover, the foregoing arrangement can permit a user to designate which channel tracks which. This feature of the present invention often can provide the user with a significant amount of flexibility when configuring a video system.
In a further aspect, the invention is directed to managing video signals in different video formats by inputting and outputting video signals through multiple channels. A user inputs a selection of a video format for each of the channels and also inputs a user designation that an output of a user-designated first channel should provide an output video signal corresponding to an input video signal input via a user-designated second channel. The input video signal is then automatically converted to the video format selected for the user-designated first channel, so as to obtain the output video signal, and the output video signal is output via the user-designated first channel.
Thus, the foregoing arrangement not only can permit a user to designate which channel tracks which, but also can allow the user to select a video format for each channel. This additional feature provides even more flexibility, in certain embodiments allowing the user to more or less arbitrarily select video formats and designate which channel(s) track which.
In a more particularized aspect, the invention is directed to managing video signals in different video formats by inputting and outputting video signals through multiple channels, capturing a single frame of an input video signal, and inputting a user selection of a video format for each channel and a user designation that an output of a user-designated first channel should output frames captured from a video signal input into a user-designated second channel. Frames captured from the video signal input into the user-designated second channel are then automatically converted into the video format selected for the user-designated first channel, and the captured frames are output, in the video format selected for the user-designated first channel, via the user-designated first channel.
The foregoing arrangement can provide many of the benefits of the above-described aspects of the invention with respect to frames captured from a live input video signal.
In a still further aspect, the invention is directed to managing video signals in different video formats by inputting a selection of an output video format and a selection of an item of video data to retrieve from a storage. The selected item of video data is then retrieved from storage and the video format in which the selected item of video data was stored is detected. Thereafter, the retrieved item of video data is automatically converted into an output video signal in the selected output video format, and the output video signal is transmitted to an output.
By virtue of the foregoing arrangement, items of video data stored in different formats typically can be retrieved and output to a single port in a single user-specified video format. As a result, much of the system reconfiguration to deal with differently formatted video signals required with conventional arrangements often can be avoided.
In a still further aspect, the invention is directed to managing video signals in different video formats by inputting and outputting video signals via multiple channels and inputting a user selection of a video format for each channel. Then, a video signal input via a first channel is automatically converted into the video format selected for a second channel, and the video signal, in the video format selected for the second channel, is output via the second channel.
The foregoing summary is intended merely to provide a brief description of the general nature of the invention. A more complete understanding of the invention can be obtained by referring to the claims and the following detailed description of the preferred embodiments in connection with the accompanying figures.